You probably already know how to express location with "在". In this article, we'll go more in depth as to how you can make idiomatic phrases using that construction. This kind of form is actually similar to some that we have in English, so it won't be too difficult.

Expressing "on the topic of" with "在...上"

This construction can be translated as "on the topic of" or "in regards to". It can be used to comment on an idea or concept. The examples below will help.

在+abstractconcepts+上，comment sentence

Examples
Zài yú fǎ shànɡ, wǒ zhī dào wǒ hái yǒu hěn duō wèn tí .
在 语法 上，我 知道 我 还 有 很多 问题。
In regards to grammar, I know I still have a lot of questions.

Expressing "under" with "在...下"

This construction can be translated (rather directly) as "under" and expresses conditions that affected the comment that comes after.

在+abstract concept+下，result/comment sentence

Examples

Expressing "on the topic of" with "在...方面"

This construction is very similar to the "在...上" above. It translates to "in relation to" or "on the topic of".
在+abstract concept+方面，comment sentence
Examples